Effects of twice-over rotational grazing on songbird nesting success in years with and without flooding
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Date
2018
Authors
Carnochan, Stacey
De Ruyck, Christopher
Koper, Nicola
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Rotational grazing is sometimes promoted for grassland bird conservation, but the benefits to wildlife have not been comprehensively documented. We examined effects of twice-over rotational grazing on nesting success of grassland songbirds in south-western Manitoba, Canada in comparison to season-long grazing. We monitored nesting attempts and collected structural vegetation data in 2011 (during a 1/300 flood event), and 2012 (average water levels), for five species of obligate grassland bird species (n=110) and one shrub-nesting species (n=41). Nesting analyses were conducted using logistic exposure models. Nesting success was 2.4-4 times lower in twice-over grazed pastures compared with season-long grazed pastures, perhaps because of the increased cattle density during the short grazing periods of the twice-over system. Nests protected by shrubs from grazing activities of cattle did not show this pattern. Grazing system did not have an effect on vegetation structure. This suggests that twice-over rotational grazing does not benefit grassland songbirds in northern mixed-grass prairies, and that caution must be taken before implementing this grazing system in areas intended to promote biodiversity conservation.
Description
Keywords
Mixed-grass prairie, rangeland management, rotational grazing, season-long grazing, twice-over grazing, nesting success
Citation
Carnochan, S. J., De Ruyck, C., and Koper, N. 2018. Effects of twice-over rotational grazing on songbird nesting success in years with and without flooding. Rangeland Ecology and Management. 71: 776-782.